Many people in the world today suffer from some type of visual impairment. Vision impairment refers to that which cannot be adequately compensated for by using corrective lenses (glasses or contact lenses) or surgery.
Low vision is generally considered to be vision poor enough to keep someone from being able to read the newspaper while wearing their habitual glasses. Visual acuity that results in this type of impairment can range anywhere from 20/20 (with a very constricted visual field) to 20/400 or worse, depending on the cause of the vision impairment. Low vision results from a variety of diseases or conditions. Age-related macular degeneration accounts for about 65% to 75% of patients requesting vision rehabilitation. Diabetic retinopathy, glaucoma, hereditary retinal degenerations or diseases such as retinitis pigmentosa, albinism, Leber's optic neuropathy, and Best's disease account for many other causes of low vision.
In order to cope with this disability, individuals work closely with a Low Vision Rehabilitation Specialist (an optometrist or ophthalmologist who has a special interest in and who has been trained in Low Vision Rehabilitation) or other professionals who specialize in specific aspects of low vision rehabilitation, such as occupational therapists, orientation and mobility instructors, educators who specialize in teaching both children and adults with poor vision, social workers and researchers. Low Vision Rehabilitation is available in most major medical centers and, in some cases, in private practices.
A Low Vision evaluation begins with a comprehensive patient history. This includes a medical, drug, social, work, and vision history. A meticulous refraction is then done to determine the patient's best possible visual acuity. Additional tests are done to determine what is needed to enable the patient to read. This correction may range from a simple pair of reading glasses to a magnifier or a complex system such as a telemicroscope or CCTV (closed circuit TV).
Other areas of the patient's lifestyle are addressed such as work needs, hobbies, social needs, recreational needs, financial and personal needs. For example, complex systems can be designed for someone who works on a computer and who needs large print or voice-activated programs. Every effort is made to enable the individual to continue working at his/her present job, or, if necessary, retraining individuals in new areas of employment.
Low Vision Rehabilitation is an approach to making the best possible use of the healthy vision remaining in the eye. The Low Vision Specialist has at her/his disposal a vast array of devices designed to help the visually impaired see better. These can include magnifiers, microscopic lenses, telescopes, electronic devices such as closed-circuit TV's, even virtual imagery. Proper lighting used in the proper manner, bold lined writing utensils and paper, large print books and magazines, large print checks and many other useful devices help with coping with vision loss.
In addition, individuals may need to work with an occupational therapist to learn to use these devices effectively. A social worker can identify community-based programs that may be beneficial. Most people who have had expert Low Vision Rehabilitation can read, write, use their computer and generally function at a relatively high level.
However, Low Vision Rehabilitation in no way affects the physical condition of the eye. It cannot make the disease better and it cannot make it worse. The goal of Low Vision Rehabilitation is to learn to use the remaining healthy vision as effectively and efficiently as possible.
A number of devices exist in the prior art for helping individuals cope with Macular Degeneration and other visual impairments. For example, U.S. Pat. No. 5,151,722 to Massof et al, incorporated by reference herein, discloses a head-mounted display for providing a monocular or binocular wide field of view. This display contains folding optics and a CRT for projecting a viewed image onto the eye. This and similar systems known as LVES (Low Vision Enhancement Systems), have a number of significant disadvantages. These systems are large, heavy and cumbersome and cannot be worn comfortably by the patient.
Because of their weight and awkward configuration, LVES systems also have the significant disadvantage that it is difficult for the patient to read effectively while wearing the unit and it is extremely difficult to move from place to place. This is because even very small amounts of movement will create image flutter and a blurring of the image that is projected onto the patient's eyes. This undesired motion and blurring of images causes the eyes to fatigue quickly and greatly increases eye strain.
These systems also cannot be used with a patient's normal prescription glasses because of their size and configuration, and the optics contained therein. Nor can they be readily optimized for changes in a patient's condition or even for different patients. Each unit must be customized for a particular condition and for a particular patient.
U.S. Pat. Nos. 5,125,046; 5,267,331, and 5,359,675, all of which are incorporated by reference herein, also disclose an image enhancement system for the visually impaired. This system is usable as a table-mounted display system or as head-mounted video spectacles. However, this system, like the LVES system, suffers from a number of significant disadvantages. These systems are also limited in that they cannot be easily reconfigured for the changing needs of the patient, and do not allow for the patient to wear his or her own prescription glasses while wearing the head-mounted enhancement system. This is a significant disadvantage in that the rehabilitation specialist cannot easily work with the patient while wearing the device to test and help improve the patient's vision. These systems also cannot be readily optimized for the needs of a different patient, but are instead designed and built for a specific application.
Because of these significant disadvantages inherent in conventional vision enhancement systems, a visual rehabilitation system is needed which significantly reduces the susceptibility of the system to motion, is easily adaptable to the changing needs of the patient, which can be readily optimized for the needs of different patients, and which will be a tremendous aid in the rehabilitation of patients coping with low vision and other visual impairments.
Thus, it should be apparent that a need exists for improved reading glasses or spectacles for aiding patients with low-vision or macular degeneration wherein the glasses use a single lens for each eye. It is an object of the present invention to provide improved low-vision enhancement systems.